In a contest which required the Gunners to have everyone performing at the peak of their powers, another disjointed display was delivered.
The struggles of recent weeks have rocked confidence within Arsene Wenger’s camp, and the problems just keep on mounting.
A trip to the Amex Stadium presented Arsenal with an opportunity to offer a positive response to those quick to criticise them on the back of successive defeats to Manchester City.
It was, however, to take just seven minutes for their frailties to be exposed by Brighton.
Cech was unable to deal with the threat posed by an early corner, allowing Lewis Dunk to fire home.
The veteran goalkeeper was then at fault again in the 26th minute, with a Glenn Murray effort squeezed under his body.
If you want to win a game away of home in the best league in the world your GK can’t concede 2 goals like I did today ... it’s simply not possible ... The team fought back but the damage was done .— Petr Cech (@PetrCech) March 4, 2018
Defeat on the south coast leaves Arsenal languishing in sixth spot in the Premier League table, 13 points adrift of the top four.
They have now suffered four successive defeats in all competitions and gone 11 games without a clean sheet.
The problems facing Wenger are obvious, with the under-fire Frenchman unable to inspire an underperforming squad into producing the level of performance required to ease some of the pressure being piled on his shoulders.
Europa League glory remains up for grabs to the Gunners, but they are set to face Italian giants AC Milan at the last-16 stage of that competition and the contrast in form between two continental rivals heading into that contest could not be more marked.
Cech, then, needs to find a way of raising his standards, along with those around him, if a season in serious danger of imploding is to be salvaged.